A conveyed object detection apparatus includes an optical sensor configured to receive light reflected by a conveyed object; a detection unit configured to use the optical sensor to acquire a detection result indicating a position, a moving speed, or a moved amount of the conveyed object in at least one of a conveyance direction in which the conveyed object is conveyed and a direction perpendicular to the conveyance direction, or a combination of the position, the moving speed, and the moved amount; and a setting unit configured to set an aperture value and an exposure time concerning the optical sensor based on the detection result.